1. Field of the Invention
The invention relates to a zip-fastener feeding device for an automatic sewing unit.
2. Background Art
From U.S. Pat. No. 4,658,740 an apparatus is known, in which a zip fastener to be sewn is seized on the entire surface by a gripping device and is transported from an insertion position to a position which is defined exactly in relation to a part of workpiece. The precise positioning of the zip fastener has to be performed even when manually bearing the zip fastener on the insertion position, which is time-consuming and which requires a certain dexterity of the operator. Further it is necessary in this case that the zip fastener to be fed is nontwisting and is available with ends, which are located parallel to each other.
From U.S. Pat. No. 2,329,991 an apparatus is known by means of which a zip fastener is fed to a sewing station of a sewing machine. To this effect a guide channel precedes the sewing station, into which guide channel the zip fastener is continuously fed manually by the operator. An accurate positioning of the zip fastener before sewing in relation to a workpiece is not possible by means of this, as the feeding of the zip fastener and its positioning in relation to the workpiece is performed progressively during the sewing process.
From U.S. Pat. No. 3,608,508 it is known to insert a zip fastener and a part of workpiece into a workpiece holder and to position them herein in relation to each other. Feeding of the zip fastener to the workpiece holder and positioning is performed manually.
From U.S. Pat. No. 4,714,038 it is known to feed a zip fastener through a guide channel to a sewing station of a sewing machine. Also in this case positioning of the zip fastener in relation to the part of workpiece is performed continuously during sewing at the workpiece station.